Runway and taxiway geometry

Four distances, four purposes

Adding a clearway cannot create landing pavement.

The declared distances

TORA is the runway length declared available and suitable for the ground run of take-off. TODA is TORA plus the available clearway. ASDA is TORA plus the available stopway. LDA is the runway length declared available and suitable for landing ground run. Annex 14 provides the declared-distance calculation framework; the AIP publishes the actual directional values.

A clearway is a defined controlled area suitable for initial climb to a specified height; it need not be paved or load-bearing and is not used for the landing roll. A stopway is a prepared rectangular area beyond TORA suitable for stopping after an abandoned take-off; it is not automatically landing distance. A displaced landing threshold reduces LDA in that direction, while the pavement before it may remain usable for take-off or the opposite-direction landing roll when declared so.

Work from the published table

If the runway is 2,400 m, the clearway 300 m, stopway 150 m and landing threshold displaced 200 m, a simple full-length example has TORA 2,400, TODA 2,700, ASDA 2,550 and LDA 2,200 m. Actual declarations can impose further reductions; intersection take-offs and obstacle restrictions can change the values.

All four equal runway length only when the relevant full-length directional declarations apply and no effective clearway, stopway or landing-threshold reduction changes them. Never reconstruct operational distances from a satellite image when a published table exists.

Strips, RESA and taxiway geometry

Safety areas and load-bearing pavement are not interchangeable.

Protecting an excursion

The runway threshold is normally at the runway extremity unless displaced for operational or obstacle reasons. A runway strip includes the runway and stopway if provided and the defined surrounding area intended to reduce damage in an excursion and protect aircraft overflying it. A RESA extends beyond the strip end to reduce damage from an undershoot/overrun. Neither is automatically available take-off or landing distance.

A rapid-exit taxiway meets the runway at an acute angle to permit a higher-speed exit and reduce occupancy. Taxiway curves need suitable radii and pavement widening to keep the main gear on the surface while the cockpit follows its reference path. Holding bays allow aircraft to wait or be bypassed without obstructing normal flow.

Holding positions protect more than paint

Runway holding positions protect the runway, obstacle surfaces and, where applicable, ILS/MLS critical/sensitive areas. Intermediate holding positions control traffic at other taxiway intersections or specified points. Road holding positions control vehicles before runway access. The protected distance can be much greater than the runway pavement edge.

An aircraft vacates only when entirely beyond the relevant holding position. A clearance onto one taxiway does not authorise crossing a marked runway holding position. Stop-bar, sign, marking and clearance information must be reconciled before proceeding.

Can you apply the rules?

Four original questions. Choose from the facts, then review the explanation.